George Entwistle, the BBC's new director general, has broken his six-day silence over the Sir Jimmy Savile sexual abuse allegations, saying he was "appalled" by what he saw in the ITV documentary on the late presenter.

In an email to staff, Entwistle said "I was appalled by the things I saw in the ITV documentary", but insisted that there was no evidence as yet to suggest that "any known wrongdoing was ignored by management" in the 1960s and 1970s.

He added it was not necessary for the BBC to launch its own independent inquiry because, having consulted the Met and other police forces examining allegations, whose number has hit 40, that would "run the risk of damaging or impeding their work". He said: "The police are the only people with the proper powers to assess criminal allegations."

Entwistle also addressed last year's decision to drop a Newsnight investigation into alleged abuse by Savile. He said that the editor of Newsnight, Peter Rippon, decided in December not to broadcast the planned 10-minute film "honestly and honourably" – and that he had seen "no evidence" that pressure was applied on him by any other part of the BBC.

At the time, the BBC was preparing a tribute to Savile, and there was a belief at Newsnight that the decision to drop the film may have involved other executives. At the time Entwistle was the BBC's director of vision, but press sources denied that he was involved.

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